This invention relates to an apparatus for chopping and discharging straw from a combine harvester of the type which includes a plurality of blade members mounted on a hub for rotation about an axis of the hub with the blade members being arranged at spaced positions along the length of the hub substantially in radial planes of the hub so as to pass between a plurality of axially spaced stationary blades again arranged in radial planes of the hub. The straw and other material discharged from the combine is fed into one side of the housing of the apparatus onto the hub and the material is carried around by the hub past the stationary blades in a chopping action. The material is then discharged from a discharge opening in the housing for collection or spreading across the field.
The present invention is particularly a modification of or an improvement over the arrangements disclosed in U.S. Pat. No. 5,232,405 issued Aug. 3, 1993 and U.S. Pat. No. 5,482,508 issued Jan. 6, 1996 of the present inventors.
These arrangements show a support plate lying in a radial plane and an additional plate or flap at right angles to the support plate to so that the additional plate lies longitudinally of the hub. The additional plate is inclined so that a radially outer edge of the additional plate lies angularly forwardly of a radially inner edge of the plate. The additional plate is welded across a trailing edge of the support plate and extends out to both sides of the support plate.
These arrangements have achieved considerable commercial and technical success and the present invention is directed to a yet further improvement which builds upon the improvement of the previous patent.
A further arrangement relevant to the present invention is that shown in U.S. Pat. No. 5,042,973 of Hammarstrand which discloses a similar chopping and discharge apparatus having rotating blade members carried on a hub and stationary blades fixed to the housing. The blade members are mounted in pairs so that a single lug carried on the hub supports a transverse pin parallel to the axis of the hub with the blade members mounted on respective sides of the lug and carried on bushings mounted on the pin. The blade members are spaced so that each blade member passes between two of the stationary blades in a cutting action. The blade members are shaped so as to be arch shaped in each cross section transverse to the length of the blade member thus defining a sharpened cutting edge at the leading edge and a sharpened cutting edge at the trailing edge with a center section of the blade bowed outwardly of a plane containing the leading and trailing edges. The blades are shown in face to face or back to back arrangements of the pairs.
A yet further arrangement is shown in U.S. Pat. No. 3,693,335 (Mathews) which shows blades which are inclined from the normal radial plane so as to extend outwardly from the hub in a direction which is inclined to the radial and axial directions.
A yet further arrangement is disclosed in U.S. Pat. No. 4,292,795 (Linn) issued Oct. 6, 1981 and U.S. Pat. No. 4,892,504 (Scott) issued Jan. 9, 1990 both of which show a straw spreader which includes a horizontal fan assembly with two types of blades which rotate about parallel vertical axes on top of a base plate and generate a suction effect tending to draw the straw downwardly into the top of the fan assembly and to expel the straw rearwardly from the back of the base plate.
It is one object of the present invention to provide an improved chopper and discharge apparatus of the same general type as shown in the above patents of the present inventor.
According to one aspect of the invention there is provided a chopper and discharge apparatus for use with a combine harvester having a combine harvester body, means for discharging separated straw from a rear discharge area of the combine harvester body, and means mounting the apparatus on the combine harvester body at a position adjacent the rear discharge area for receiving straw therefrom, the apparatus comprising;
a housing having a feed opening and a discharge opening, a plurality of stationary blades mounted in the housing in axially spaced positions therealong, the stationary blades lying in parallel radial planes;
a chopping assembly mounted in the housing and comprising a hub member mounted for rotation about a longitudinal axis of the hub member and a plurality of blade members mounted on the hub member for rotation therewith about said axis, each blade member projecting generally outwardly from the hub member substantially in a radial plane of said axis, the blade members being arranged at spaced positions along the length of the hub member such that rotation of the hub member causes the blade members to pass generally between the stationary blades in a cutting action;
the feed opening being arranged to deposit the material onto the chopping assembly in a direction generally inwardly toward the axis and the discharge opening being arranged to allow discharge of the material generally radially outwardly from the chopping assembly;
each of at least some of the blade members each including a blade formed from a flat strip which has a substantially planar mounting portion mounted on the hub member to lie in a radial plane of the hub member an intermediate portion and a substantially planar blade portion wherein the strip is twisted within the intermediate portion about a line longitudinal of the strip such that the plane of the blade portion lies at an angle to the radial plane and such that one side edge of the blade portion lies in a radial plane offset axially from a radial plane containing the other of the side edges of the blade portion.
Preferably the strip of the twisted blade members is twisted about a center line.
Preferably the strip is of substantially constant width.
In some cases, the plane of the blade portion is at an angle of 90 degrees to the radial plane so that it has little or no tendency to direct air longitudinally of the axis of the hub member.
In other cases, the plane of the blade portion is at an angle less than 90 degrees to the radial plane such that one side edge of the blade portion is angularly advanced relative to the other side edge so that the rotation of the blade members about the axis with the hub member tends to direct air longitudinally of the axis.
Preferably the side edges of the blade portion are sharpened and particularly each side edge is sharpened to a sharp edge lying in one surface of the blade portion which may be the same surface of the blade portion.
Preferably the blades are arranged in pairs with each one of a pair being arranged on a respective side of one of the stationary blades.
Where the blades are arranged in pairs and the angle of the blade portion is such that it generates axial air flow, the blades are preferably arranged with the angle of one of the pair being opposite to the angle of the other.
When arranged in pairs, each pair is preferably mounted on a respective one of a plurality of lugs mounted on the hub member at spaced positions thereon, each lug having a pin mounted thereon with a pin axis of the pin parallel to the axis of the hub member such that the pair of blade members can pivot on the pin about the pin axis.
In one arrangement, some additional flat blade members are carried on the hub member each of which is defined solely by a planar cutting portion lying in a radial plane of the hub axis. In this case there may be more flat blade members adjacent a center of the hub member than adjacent ends of the hub member and thus more angled blades adjacent the ends.
Where the hub member carries some flat blade members and the blade members are arranged in pairs, some of the pairs preferably include one flat blade member and one twisted blade member.
In this arrangement there are preferably more flat blade members adjacent a center of the hub member than adjacent ends of the hub member.
Preferably at least some of the blade members at each end of the hub member are arranged such that the movement of air caused thereby is directed toward the respective end so as to assist in directing chopped material outwardly from that end.
In this case, the blade members at each end of the hub member are preferably arranged such that the total tendency of the movement of air caused thereby is directed toward the respective end.